The present invention relates in general to the design and construction of tubing assemblies which are used in closed fluid systems. More particularly, the present invention relates to turbocharger oil drain tubes having an integral seal at the engine block.
A turbocharged engine requires a steady flow of clean lubricating oil from the engine to the bearings of the turbocharger. It is just as important to return the lubricating oil from the turbocharger to the engine crankcase to insure that a sufficient supply of oil is available for circulation throughout the engine and turbocharger. A turbocharger oil drain tube provides the conduit for returning the lubricating oil to the crankcase.
In the past, designers of turbocharger oil drain tubes have generally used a combination of rigid preformed tubes and flexible hoses to provide a conduit between an engine and a turbocharger. One approach is to provide an oil drain tube which utilizes a first rigid tube and a second rigid tube that are connected by a flexible hose. The engine block has a bore and one end of the first rigid tube is press fit therein, and one end of the second rigid tube is attached to the turbocharger by a clamp. The two rigid tubes are connected in fluid communication by a flexible hose which utilizes hose clamps to compress the inner surface of the hose against the outer surface of the rigid tube, thereby creating a fluid-tight conduit. A second approach is to provide an oil drain tube which utilizes a single preformed rigid tube connected between the engine and the turbocharger by a pair of short flexible hoses, one each at opposite ends of the rigid tube. The flexible hoses connect the rigid tube to mounting flanges on the engine and turbocharger. Hose clamps compress the inner surface of each short flexible hose against the outer surface of the rigid tube and the associated mounting flanges of the engine and turbocharger, thereby creating a fluid-tight seal.
These two approaches of providing a turbocharger oil drain tube which utilize the combination of rigid tubes and flexible hoses have several common limitations. The first limitation is that oil leakage is inherent at the flexible hose connections. The oil leakage is generally attributed to a combination of assembly misalignment, surface imperfections in the adjoining pieces, and a hostile operating environment which physically degrades the hose. A second limitation is the increased cost of installing an oil drain tube that is comprised of a combination of rigid tubes and flexible hoses. A service technician's time to install an oil drain tube is greatly increased by having to align and interconnect the rigid tubes and flexible hoses. Associated concerns in the design of fluid conduits relate to the specific point to point mounting or connection of the conduit.
There are a variety of fluid-tight couplings and flange devices which have been conceived of over the years. The following listing of references is believed to be representative of such earlier designs:
______________________________________ PATENT No. PATENTEE ISSUE DATE ______________________________________ 3,001,804 Tomlinson Sept. 26, 1961 et al. 3,584,902 Vyse, June 15, 1971 4,707,000 Torgardh, Nov. 17, 1987 4,844,512 Gahwiler, July 4, 1989 5,104,157 Bahner, April 14, 1992 4,850,622 Suzuki, July 25, 1989 APPLICATION APPLICANT PUBLICATION DATE NO. DAYCO CORP. AUGUST 18, 1983 PCT/US82/0156 ______________________________________
Even with a variety of earlier designs, there remains a need for a flexible, unitary turbocharger oil drain tube that is easy to install and which eliminates the oil leakage around the hose connection at the turbocharger and engine block. The present invention satisfies this need in a novel and unobvious way.